The second main contribution of this paper is the logical characterization of net bisimilarity \(\sim _n\)  in terms of a new modal logic,
called NML (acronym of net modal logic), which can be seen as a generalization of Hennessy-Milner Logic [1]}
with an operator of parallel composition of formulae (e.g., \(F_1 \otimes F_2\) ), and with a generalization of the HML modal
operator \(\mbox{$\langle a \rangle $}\)  to \(\mbox{$\langle a \rangle ^h_k$}\) , which
stands for the executability of a net transition labeled \(a\)  with pre-set of size \(h\)  and post-set of size \(k\) .
We prove that two markings are net bisimilar if and only if they satisfy the same NML formulae.
